Can't use "Selection Popup Menu" Alt + Right Click (v2.76)
You have to have multiple objects in your scene. Sometimes the scene is so crowded, that some objects overlap each other, so you press the Alt+RMB to choose the desired one. In my case I have the main model, the bones (metarig) and the rough proxy mesh. As you can see, when I hover the cursor over object and press Alt+RMB the pop up menu appears.